Electronic sight for firearm, and method of operating same

ABSTRACT

A firearm sight receives information regarding a factor, and then automatically adjusts the relative positions of a digital reticle and an image on a viewing section to compensate for the influence of the factor on a projectile trajectory. A different feature involves automatically adjusting a characteristic of the reticle based on the image. Another feature involves automatically adjusting the digital image to distinguish a portion thereof aligned with the reticle from an adjacent portion thereof. Yet another feature involves causing the firearm sight to generate an audible sound. Still another feature involves presenting information on the viewing section which represents the position of the firearm sight on the surface of the earth.

TECHNICAL FIELD OF THE INVENTION

This invention relates in general to a device which facilitates accurateaiming of a firearm and, more particularly, to a firearm sight which ismounted on the firearm, and through which a user observes a potentialtarget.

BACKGROUND OF THE INVENTION

Over the years, various techniques and devices have been developed tohelp a person accurately aim a firearm, such as a rifle or targetpistol. One common approach is to mount on the firearm's barrel a sightor scope, through which the person views the intended target inassociation with a reticle, often with a degree of magnification.Although existing firearm sights have been generally adequate for theirintended purposes, they have not been satisfactory in all respects.

For example, when a sight is first mounted on the barrel of a firearm,it needs to be aligned or “zeroed” with the firearm barrel, typicallythrough a trial and error process. For example, a person may shoot oneor more bullets at a target which is a known distance away, identify theextent to which the bullets strike the target at locations offset fromthe location at which the person was aiming, and then adjust thealignment of the sight in relation to the firearm in a manner intendedto eliminate the offset. This sequence of steps is repeated in aniterative manner, until bullets are striking the target at substantiallythe same location where the person is aiming.

This process results in alignment of the sight and firearm for onespecific set of conditions. However, during subsequent use of thefirearm and sight, for example when hunting, a variety of conditions canvary from the conditions that existed during the alignment or zeroingprocess, and can thus affect the trajectory of a bullet. These includefactors such as temperature, pressure, humidity, wind speed and winddirection, all of which affect the density of air and thus the dragexerted on the bullet, and drag in turn influences the trajectory.Further, the tilt of the firearm barrel can influence the direction inwhich gravity acts on the bullet in relation to the initial trajectoryof the bullet, and this can in turn influence how gravity affects theoverall trajectory of the bullet. Still another factor is that theactual range or distance to a target is usually different from the rangeor distance that exists during the alignment or zeroing process.

Consequently, even after a sight has been aligned with respect to afirearm under known conditions, a person who thereafter uses the sightto aim the firearm under other conditions needs to make appropriatemental and visual compensation. In this regard, the person musttypically aim the reticle of the sight at a point which is offset fromthe desired impact point of the bullet on the target. For example, ifthe range to the target is much longer than the range used to zero thesight, the person may need to aim the reticle of the sight at a pointwhich is located above the target. Similarly, if there is wind blowingfrom the left or right, the person may need to aim the reticle of thesight at a point which is offset leftwardly or rightwardly from thetarget, in order to compensate for the effect which the wind will haveon the trajectory of the bullet. Some reticles include markings at knownangular increments, to help a person make an appropriate offset, butthere is still a high degree of mental guesswork involved.

Some persons may adjust knobs on the sight in order to adjust thealignment of the sight away from its initial setting, so as tocompensate for the current conditions. Several different tables of datamay be needed to determine appropriate adjustments for respectivedifferent factors, and the values from these multiple tables must becombined in order to determine a number of turns to be effected for eachof two or more knobs. But this approach is complex, cumbersome and slow,and thus impractical for most real-world situations. For example, animaltargets do not usually wait around while a hunter goes through thisadjustment process. Moreover, even this approach usually involves asignificant degree of mental guesswork as to what the current conditionsare.

Given the variety of different factors that can influence the trajectoryof a bullet, attempts of this type to mentally and visually effectcompensation involve a significant degree of estimation and guesswork,and frequently result in the bullet missing the target altogether, orhitting the target at a location which is spaced from the desired impactpoint. A further problem is that, at any given point in time, existingsights use a selected reticle which has various predeterminedcharacteristics, such as color, shape, size and/or brightness. Thus, forexample, if the reticle is a dark color and the target also happens tobe a dark color, it may be very difficult to distinguish the reticlefrom the target when the reticle is aligned with the target.

Still another consideration is that, when looking through an existingsight, it is sometimes difficult to identify and/or distinguish apotential target from other portions of the scene being viewed throughthe sight. Yet another factor is that a hunter or other person using afirearm and sight often has to carry other separate items of equipment.Examples include paper maps, compasses, laser rangefinders,self-contained global positioning system (GPS) devices, and several gamecalls designed to attract various different types of animals that arepotential targets.

SUMMARY OF THE INVENTION

From the foregoing it may be appreciated that a need has arisen for afirearm sight which avoids some or all of the disadvantages that areassociated with pre-existing sights.

One form of the invention relates to operation of a firearm sight, andinvolves: providing on a viewing section an image of a scene inassociation with a digital reticle; receiving information representing afactor that can influence a projectile trajectory; and automaticallyadjusting a position of the digital reticle in relation to the image aspresented on the viewing section so as to compensate for the extent towhich the factor would influence a projectile trajectory.

A different form of the invention involves: presenting for a user on aviewing section an image of a scene in association with a digitalreticle; and automatically adjusting a characteristic of the reticle inresponse to the image.

Another form of the invention involves: presenting for a user on aviewing section a digital image of a scene in association with areticle; and automatically adjusting the digital image to distinguish afirst portion of the image which is substantially aligned with thereticle from a second portion of the image which is adjacent the firstportion thereof.

Yet another form of the invention involves generating of an audiblesound from a firearm sight.

Still another form of the invention relates to operation of a firearmsight having a display, and involves: receiving electromagnetic signals;determining in response to the received electromagnetic signals aposition of the firearm sight on the surface of the earth; andpresenting information on the display which represents the position ofthe firearm sight on the surface of the earth.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present invention will be realized fromthe detailed description which follows, taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a diagrammatic perspective view of an apparatus which is adigital rifle sight, and which embodies aspects of the presentinvention;

FIG. 2 is a diagrammatic fragmentary perspective view which shows anopposite side of the rifle sight of FIG. 1;

FIG. 3 is a diagrammatic view of a switch panel of the rifle sight ofFIG. 1, in an enlarged scale;

FIG. 4 is a block diagram of the rifle sight of FIG. 1, and showscertain portions thereof which are not visible in the views of FIGS.1-3;

FIG. 5 is a diagrammatic view of a color display which is a component ofthe rifle sight of FIG. 1, during a normal operational mode;

FIG. 6 is a diagrammatic view of the display during a menu mode, andshows a list of menu selections;

FIG. 7 is a diagrammatic view of the display, showing a reticleselection screen;

FIG. 8 is a diagrammatic view of the display, showing a screen used toset elevation and windage offsets for a currently-selected reticle;

FIG. 9 is a diagrammatic view of the display, in a mode used to displayimages and/or video clips stored within a memory of the rifle sight;

FIG. 10 is a diagrammatic view of the display, showing an options menu;

FIG. 11 is a diagrammatic view showing an entire image detected by animage detector of the rifle sight, and showing a portion of this imagewhich is currently being presented on the display;

FIG. 12 is a diagrammatic view similar to FIG. 11, but showing how thesight has automatically shifted the displayed image relative to thedetected image so that the reticle indicates the expected impact pointof a bullet within the detected scene;

FIG. 13 is a diagrammatic view similar to FIG. 12, but showing thereticle centered on the target;

FIG. 14 is a diagrammatic view showing the detected image and thedisplayed portion of this image, under circumstances where the rifle andsight are tilted a few degrees about a longitudinal axis, and when anautomatic ballistic compensation feature is disabled;

FIG. 15 is a diagrammatic view similar to FIG. 14, but showing how thesight has automatically repositioned the displayed portion of thedetected image so that the reticle is centered over the expected impactpoint; and

FIG. 16 is a diagrammatic view similar to FIG. 15, but showing how auser has centered the adjusted reticle on the target.

DETAILED DESCRIPTION

FIG. 1 is a diagrammatic perspective view of an apparatus which is adigital rifle sight 10, and which embodies aspects of the presentinvention. Although the sight 10 is referred to herein as a “riflesight”, it can actually be used not only with rifles, but also withother types of firearms, such as target pistols. The sight 10 includes arail mount 12, which can fixedly and securely mount the sight 10 on thereceiver or mounting rail of a firearm.

The sight 10 includes a housing 14, which has at a front end thereof anobjective lens section 16 that includes at least one lens 17, and whichhas at a rear end thereof an eyepiece optics section 18. The housing 14has an access panel 21, which is removably held in place by a thumbscrew22. The access panel 21 can be removed in order to provide access to aninternal compartment that contains selected components, as discussed inmore detail later.

The sight 10 has a laser rangefinder 26, which is fixedly mounted on oneside thereof. The rangefinder 26 uses technology of a known type, andcan determine the distance to a target by transmitting a laser beam andthen analyzing reflected energy. A global positioning system (GPS)antenna 28 is provided on top of the housing 14, so that the sight 10can receive electromagnetic GPS signals of a known type emitted by GPSsatellites. Using these received GPS signals, the sight 10 can determinein a known manner its precise location on the surface of the earth, toan accuracy within a few feet.

A wind sensor 31 of a known type is mounted on top of the housing 14 ofthe sight 10. The wind sensor 31 has a spherical shell with a pluralityof spaced openings through it, and has a sensor arrangement disposedwithin the shell. The wind sensor 31 is capable of detecting both thespeed and the direction of any ambient wind. In the disclosedembodiment, the wind sensor 31 is a component which can be obtainedcommercially under the tradename OMNIPROBE from Aeroprobe Corporation ofBlacksburg, Va. However, the wind sensor could alternatively beimplemented with any other suitable device.

FIG. 2 is a diagrammatic fragmentary perspective view which shows anopposite side of the rifle sight 10 of FIGURE. The sight 10 has somecircuitry within the housing 14, including a circuit board 41. Tworemovable batteries 42 and 43 of a commercially available type areprovided to power the circuitry. The access panel 21 (FIG. 1) can beremoved in order to obtain access to the batteries 42 and 43 so thatthey can be replaced. Although the batteries 42 and 43 in the disclosedembodiment are replaceable, it would alternatively be possible to userechargeable batteries.

As shown diagrammatically in FIG. 2, the sight 10 includes a removablememory card 46. In the disclosed embodiment, the memory card 46 is amemory card of the type commonly used in digital camera, for example anindustry-standard card of the type commonly referred to as a Multi-MediaCard (MMC) or a Secure Digital (SD) card. However, it wouldalternatively be possible to use any other suitable device for theremovable memory card 46. The access panel 21 (FIG. 1) can be removed inorder to obtain access to the memory card 46, so that it can bereplaced.

The housing 14 includes a wall structure 49, which separates a portionof the interior of the housing 14 from the remainder of the interior. Inparticular, the wall structure 49 defines a compartment 51, which is apart of the interior of the housing 14 that is sealed off from theremainder of the interior of the housing. The housing 14 has a wallportion at the rear end thereof with a cluster of small openings 52extending through it, in order to provide fluid communication betweenthe interior of the compartment 51 and the ambient atmospheresurrounding the sight 10.

A further circuit board 56 is provided within the compartment 51, and iselectrically coupled to the circuit board 41 through the wall 49 by aconnector 57. The circuitry on the circuit board 56 includes a tiltsensor 61, which can detect the degree of tilt or roll of the sight 10about the longitudinal axis of the sight 10, and also the degree of tiltor pitch of the sight 10 about a horizontal axis extending transverselyto the longitudinal axis. In the disclosed embodiment, the tilt sensor61 is implemented with a component that is available commercially aspart number ADXL203 from Analog Devices, Inc. of Norwood, Mass. However,the tilt sensor 61 could alternatively be implemented with any othersuitable device.

The circuitry on the circuit board 56 also includes a pressure sensor62, which can sense the ambient barometric pressure in the vicinity ofthe sight 10. In the disclosed embodiment, the pressure sensor 62 isimplemented with a commercially available part, which is anMPX411SA/MPXA411SA-series device available from Motorola Inc. ofSchaumburg, Ill. However, the pressure sensor 62 could alternatively beimplemented with any other suitable device.

The circuitry on the circuit board 52 further includes a sensor 63,which can detect the ambient temperature and the ambient humidity in thevicinity of the sight 10. In the disclosed embodiment, the temperatureand humidity sensor 63 is implemented with a device which is availablecommercially as part number HIH-3602-C from the Sensing and Controldivision of Honeywell, Inc. in Freeport, Ill.

A further component of the circuitry on the circuit board 56 is anaccelerometer 66. In the disclosed embodiment, the accelerometer 66 is adevice which can be obtained commercially as part number ADXL105 fromAnalog Devices, Inc. However, the accelerometer 66 could alternativelybe implemented with any other suitable device. The accelerometer 66 is ahighly sensitive sensor that can detect the relatively small shock wavewhich occurs when the firing pin strikes a cartridge within a firearm onwhich the sight 10 is mounted. Of course, when the firing pin strikesthe cartridge, it triggers combustion of the gun powder or otherpropellant disposed within the cartridge, so as to expel a bullet orother projectile from the cartridge and the firearm.

When the firing pin strikes a cartridge, the output from theaccelerometer 66 has a frequency spectrum which is different from thefrequency spectrum produced in response to combustion of the materialwithin the cartridge. Consequently, the circuitry in the sight 10 candistinguish a shock wave representing the firing pin striking acartridge from a different shock wave representing some other type ofevent, such as combustion within a cartridge.

The combustion within a cartridge produces a shock wave or recoil whichis many orders of magnitude larger than the shock wave produced when thefiring pin strikes the cartridge. The accelerometer 66 has thesensitivity and bandwidth needed to detect the relatively small shockwave which is produced when the firing pin strikes a cartridge, and alsohas the durability needed to withstand the much larger shock wave orrecoil which is produced by the ensuing combustion within the cartridge.

The circuitry on the circuit board 56 further includes a gyroscope 67,which is referred to here as a rate gyro. In the disclosed embodiment,the rate gyro 67 is implemented with a pair of known devices, which areeach available commercially as part number ADXRS150 from Analog Devices,Inc. However, it would be alternatively be possible to implement therate gyro 67 with any other suitable device. The two ADXRS150 parts areoriented so that one is orthogonal to the other, such that these partsdetect angular movement about respective vertical and horizontal axes.Consequently, the rate gyro 67 is capable of detecting the rate ofangular movement of the sight 10 about a not-illustrated vertical axisand a not-illustrated horizontal axis. Stated differently, the rate gyro67 is a highly sensitive device which is effectively capable ofdetecting the rate of movement of the sight 10 in directions transverseto a not-illustrated center line of the objective lens section 16.

A small loudspeaker 68 is supported on the circuit board 56, inproximity to the openings 52 through the housing 14. The circuitrywithin the sight 10 is capable of using the speaker 68 to emit throughthe opening 52 a selected audio sound, such as an animal sound of a typewhich is commonly known as a game call, and which is intended to attracta prospective target to a hunter who is using the sight 10.

Although the disclosed embodiment uses the speaker 68 within the housing14, it would alternatively be possible to use a larger speaker disposedexternally of the housing 14, in order to permit a louder sound to beemitted, so that the sound will travel a longer distance. In thisregard, a larger speaker could be provided in a further housing which isexternal to and separate from the housing 14, and which is coupled bywires to a not-illustrated connector provided somewhere on the housing14, for example within the compartment behind the access panel 21 (FIG.1). Where a speaker is provided within such an external housing, itwould also be possible to provide a battery-operated amplifier withinthe same housing, in order to amplify the audio signals before they aresupplied to the speaker.

A switch panel 76 is provided on top of the housing 14, and has severalmanually-operable switches. FIG. 3 is a diagrammatic view of the switchpanel 76, in an enlarged scale. The switch panel 76 includes a powerswitch 78. Manual operation of the power switch 78 causes it to togglebetween on and off states, in which it respectfully provides andinterrupts a flow of electrical power from the batteries 42-43 to thecircuitry within the sight 10.

A manually operable MENU switch 81 is provided in the center of theswitch panel 76, for a purpose discussed later. The MENU switch 81 issurrounded by an annular four-way switch 82, which is used for variouspurposes discussed later. Pressing any of the four sides 86-89 of theswitch 82 produces a respective different electrical signal within thesight 10. The switch panel 76 also includes a SHUTTER switch 83, and aGAME CALL switch 84, both of which are discussed later.

FIG. 4 is a block diagram of the rifle sight 10, and shows certaininternal portions thereof which are not visible in the external views ofFIGS. 1-3. Various elements which have already been discussed above areshown diagrammatically in FIG. 4, and are identified with the samereference numerals used above.

With reference to FIG. 4, the objective lens section 16 of the sight 10has a field of view (FOV) of 5°, but it could alternatively have someother field of view. The sight 10 includes an image detector 102, andthe objective lens section 16 is operable to image a remote scene ortarget 101 onto the image detector 102. In the disclosed embodiment, theimage detector 102 is a complementary metal oxide semiconductor (CMOS)device of a known type. It has a plurality of detector elements arrangedin a two-dimensional array of 2352 columns by 1728 rows. Each detectorelement corresponds to a respective pixel in each image produced by theimage detector 102, and the image detector 102 is thus effectively a 4.1megapixel detector. It would alternatively be possible to implement theimage detector 102 using any other suitable device, including a devicehaving a larger or smaller number of detector elements, or a deviceother than a CMOS image detector, such as a charge coupled device (CCD)array.

The image detector 102 produces a sequence of digital color images ofthe scene 101, and this sequence of images is supplied to a processingsection 106. Although the image detector 102 of the disclosed embodimentproduces color images, the images could alternatively be monochromeimages, or black and white images. The processing section 106 includes aprocessor 107 of a known type, and a memory 108.

The memory 108 in FIG. 4 is a diagrammatic representation of the memoryprovided for the processor 107, and may include more than one type ofmemory. For example, the memory 108 may include a read only memory (ROM)which contains a program executed by the processor 107, as well as datathat does not change during program execution. The memory 108 can alsoinclude some random access memory (RAM), in which the processor canstore data that changes dynamically during program execution. The memory108 can also include some semiconductor memory of the type commonlyknown as “flash” RAM, which is random access memory that will maintaininformation stored in it through a power loss. Memory of this type iscommonly used in devices such as memory cards for digital cameras.

The processing section 106 further includes a reformatter ill of a knowntype, which is capable of taking an image generated by the imagedetector 102 and reformatting the image to a lower resolution that issuitable for presentation on a display with a lower resolution than theimage detector 102. Images processed by the reformatter 111 are suppliedto a display drive circuit 116, which in turn drives a color display117. In the enclosed embodiment, the color display 117 is a liquidcrystal display (LCD) of a known type, and has a plurality of pixelelements that are arranged in a two-dimensional array of 640 columns by480 rows. The display 117 could, however, have a larger or smallernumber of pixel elements, or could be any other suitable type of displaydevice, such as an organic light emitting diode (OLED) display, a liquidcrystal on silicon (LCOS) display, or a micro-electro-mechanical system(MEMS) reflective display. It will be noted that, in the disclosedembodiment, the image detector 102 has more than thirteen times as manypixels as the display 117. This facilitates various features which arediscussed later.

The eyepiece optics 18 includes optics of a known type, which permit thedisplay 117 to be comfortably viewed by an eye 123 of a person who isusing the sight 10 in association with a firearm. In the disclosedembodiment, the eyepiece optics section 18 has a FOV of 15°, but itcould alternatively have some other suitable FOV. The eyepiece opticssection 18 of the disclosed embodiment could optionally be omitted forapplications that allow a person to directly view the display 117 with aviewing distance greater than about 8 inches, because comfortableviewing is possible with little or no accommodation for the eye.

The above-mentioned tilt sensor 61, pressure sensor 62, temperature andhumidity sensor 63, accelerometer 66, rate gyro 67 and speaker 68 areeach operationally coupled to the processing section 106 through the,connector 57. As mentioned above, the removable access panel 21 can bemanually removed, in order to obtain access to a compartment in which itis possible to access the batteries 42-43 or the memory card 46, so thatthey can be replaced.

The compartment behind the access panel 21 also includes an externalpower connector 141, which can be coupled to an external source ofpower, such a converter that converts alternating current (AC) to directcurrent (DC). The batteries 42-43 and the external power connector areeach coupled to the power switch 78. When the power switch 78 isrespectively switched on and off, it respectively permits and interruptsa flow of current from the batteries 42-43 and/or the connector 141 tocircuitry 143 that is disposed within the sight 10, and that requireselectrical power in order to operate.

The compartment behind the access panel 21 also includes a connector146, which is coupled to the processing section 106. The connector 146,and signals transmitted through it, conform to a well-known industrystandard which is commonly referred to the Universal Serial Bus (USB)standard. However, it would be alternatively be possible to use anyother suitable type of connector and communication protocol, such as astandard serial connector and communication protocol, or a standardparallel connector and communication protocol. When the connector 146 iscoupled to the USB bus of a not-illustrated computer, the sight 10automatically detects that it has been coupled to the bus, and acts as aUSB mass storage slave device with respect to the USB bus. Connector 146can be used to upload image data or video data from the sight 10 to anot-illustrated computer. In addition, the connector 146 can be used todownload various types of information from a computer into the sight 10.For example, information from a computer can be downloaded through theprocessing section 106 into the removable memory card 46.

The compartment behind the access panel 21 also includes yet anotherconnector 148, which can be used to transfer video information from thesight 10 to an external device. In the disclosed embodiment, theconnector 148 is a standard component of the type commonly known as anRCA jack, and information transmitted through it conforms to either oftwo industry video standards which are commonly known as the NationalTelevision Standards Committee (NTSC) protocol, and the PhaseAlternating Line (PAL) protocol. However, it would be possible toalternatively use any other suitable type of connector, and videoinformation could be transferred according to any other suitableprotocol.

It will be noted from FIG. 4 that the wind sensor 31 and the laserrangefinder 26 are each operably coupled to the processing section 106.The circuitry within the sight 10 includes a GPS circuit 156, which iscoupled to the GPS antenna 28, and to the processing section 106. TheGPS circuit 156 is configured to receive GPS radio signals through theGPS antenna 28, and to convert the signals in a known manner into a formthat is suitable for use by the processing section 106.

FIG. 5 is a diagrammatic view of the color display 117, as seen by theeye 123 of person looking through the eyepiece optics section 18 of thesight 10, during a normal operational mode of the sight 10. In thenormal operational mode, the display 117 presents a view of the scene101, as captured by the image detector 102 through the objective lenssection 16. The scene 101 is shown diagrammatically by broken lines inFIG. 5.

The processing section 106 superimposes on the image of the scene 101 areticle 201-205. IN FIG. 5, the reticle includes a small center circle201, and four lines 202-205 which each extend radially with respect tothe circle 201, and which are offset by intervals of 90°. The reticle201-205 is one example of a variety of different reticles that can beused by the sight 10. In the disclosed embodiment, the sight 10 includestwo predefined reticles. One is the reticle shown at 201-205, which isreferred to as a “CROSSHAIR” reticle. The other predefined reticle is astandard military reticle which is identified in the sight 10 as the“MIL DOT” reticle.

In addition, electronic definitions of two custom reticles can bedownloaded to the memory card 46 of the sight 10 through the USBconnector 146. These custom reticles are referred to as “CUSTOM1” and“CUSTOM2”, and can have almost any configuration desired by a user. Inparticular, a reticle with virtually any desired configuration can becreated by a user in a separate computer, or can be obtained by the userfrom the sight manufacturer, or from a third party through a networksuch as the Internet. Each such custom reticle can then be selectivelyelectronically downloaded in digital form through the connector 146 andinto the memory card 46.

Thus, at any given point in time, the sight 10 will include between twoand four definitions of reticles. The user selects one of these reticledefinitions, and the selected reticle is used by the sight 10 until theuser selects a different reticle definition. During normal operation,the processing section 106 takes the selected reticle, and digitallysuperimposes it on images that will be sent to the display 117. In FIG.5, the reticle 201-205 has been superimposed on the image, in a mannerso that the reticle is centered on the display 117. However, asdiscussed in more detail later, there are modes where the position ofthe reticle on the display 117, and thus the position of the reticlerelative to the image of the scene 101, may be offset from a centeredposition.

As shown in FIG. 5, the display 117 provides some additional informationin the normal operational mode. In this regard, the lower left corner ofthe display 117 includes a windage or azimuth adjustment value 211,which is a positive or negative number representing a horizontal offsetof the reticle 201-205 from an initial alignment or “zeroed” condition,as discussed later. Similarly, the lower right corner of the display 117includes an elevation or pitch adjustment value 212, which is a positiveor negative number representing a vertical offset of the reticle 201-205from its initial alignment or “zeroed” condition, as discussed later.During normal operation, if no alignment adjustments have been made fromthe “zeroed” condition, the windage and elevation adjustment valuesdisplayed at 211 and 212 will each be zero.

The upper right corner of the display 117 has a battery charge indicator213, which is divided into five segments, and which is used to indicatethe state of the batteries 42-43. In particular, when the batteries arenew, all five segments of the battery charge indicator 213 arehighlighted. Then, as the batteries 42-43 become progressivelydischarged, the number of the segments of the battery charge indicator213 which are highlighted will progressively decrease.

The upper left corner of the display 117 presents a count indicator 214,which relates to the fact that the processing section 106 can storesingle images and/or short video clips in the removable memory card 46,as discussed later. The count indicator 214 is an indication of how manyadditional images or video clips can be stored in the space whichremains available for storing images within the memory card 46, atcurrently selected resolution and compression settings (which arediscussed later).

The top center portion of the display 117 has a capture mode indicator215, and a resolution indicator 216. The capture mode indicator 215indicates which of two capture modes is currently in effect. Inparticular, a user can select whether a specified event will cause thesight 10 to store in the memory card 46 a single image, or a short videoclip that contains several successive images. If the user has selectedthe video clip mode, then the indicator 215 reads “VID”.

Otherwise, the indicator 215 reads “IMG”.

The user has the capability to select which of two resolutions will beused for stored images or video clips. If the user selects the higherresolution, then the indicator 216 reads “HI RES”, and each single imageor video clip image contains 1920 by 1440 pixels. On the other hand, ifthe user selects the low resolution, the indicator 216 reads “LO RES”,and each single image or video clip image contains 640 by 460 pixels.Alternatively, it would be possible to use different resolutions eachinvolving some other number of pixels, and/or a different number ofresolution selections.

The bottom portion of the display 117 has a firing pin detectionindicator 217. The indicator 217 reflects whether or not the sight 10 iscurrently enabled to detect an event where the firing pin in anassociated rifle strikes a cartridge, as discussed later. When thiscapability is enabled, then the indicator 217 reads “FP”. Otherwise, theindicator 217 is blank.

The bottom central portion of the display 117 also includes a rangeindicator 218, which displays a value that the sight 10 is currentlyusing as the distance to a target or scene 101. In FIG. 5, the letter“M” in the range indicator 218 means that the displayed numeric value isin meters. However, the distance to the target could alternatively bepresented in any other desired units, such as yards.

The central portion of the display 32 has an angular error indicator231. The indicator 231 is a circle which is larger than and concentricto the circle 201 at the center of the reticle 201-205. The diameter ofthe indicator 231 is increased and decreased in response to informationreceived from the rate gyro 67. In particular, the processing section107 monitors the output of the rate gyro 67. Typically, the user will beaiming the firearm and attempting to keep the reticle center 201accurately centered on a portion of the scene 101 which is considered tobe a target.

If the user happens to be holding the firearm very steady, the rate gyro67 will detect little or no angular motion of the sight 10 and thefirearm, or in other words little or no movement thereof transverse tothe centerline of the objective lens section 16. Consequently, theprocessing section 107 will present the indicator 231 as a circle ofrelatively small diameter, in order to indicate to the user that thefirearm is being relatively accurately held on the selected target. Onthe other hand, if the user is having difficulty holding the firearmsteady, the rate gyro 67 will detect the greater degree of angularmovement of the firearm and sight. Consequently, the processing section107 will display the indicator 231 with a larger diameter, therebyindicating that the reticle center 201 is not being held on the targetas accurately as would be desirable.

In the disclosed embodiment, the change in the diameter of the indicator231 is continuous. In other words, a progressive increase in the amountof angular movement of the firearm and sight results in a progressiveincrease in the diameter of the indicator 231. Conversely, a progressivedecrease in the amount of angular movement of the firearm and sightresults in a progressive decrease in the diameter of the indicator 231.The user will thus endeavor to squeeze the trigger of the firearm at apoint in time when the reticle center 201 is centered on the target, andwhen the indicator 231 has a relatively small diameter to indicate thatthe firearm is currently being held very steady.

During the normal operational mode, pressing the portions 88 or 89 (FIG.3) of the four-way switch 82 will increase or decrease the brightness ofthe display 117. In addition, during the normal operational mode,pressing the portions 86 or 87 (FIG. 3) of the four-way switch 82 willproduce a zoom effect. In particular, pressing one portion will increasethe zoom factor, and pressing the other portion will decrease the zoomfactor. In the disclosed embodiment, the zoom is continuous, and canrange from 1× to 4×, but it would alternatively be possible to use anon-continuous zoom with several discrete levels, and/or some other zoomrange.

As explained above, the image detector 102 has more pixels than thedisplay 117. When the sight 10 is operating at a zoom factor of 4×, aportion is extracted from each image produced by the image detector 102,with a size of 640 by 480 pixels. This portion is then displayed on thecolor display 117, with each pixel from the extracted portion beingmapped directly on a one-to-one basis to a respective pixel of thedisplay 117.

When the zoom factor is at 1×, the reformatter 111 essentially takes anentire image from the image detector 102, divides the pixels of thatimage into mutually exclusive groups which each have 16 pixels arrangedin a 4 by 4 format, averages or interpolates the 16 pixels of each groupinto a single calculated pixel, and then maps each of the calculatedpixels to a respective corresponding pixel of the display 117.Similarly, when the zoom factor is at 3×, the reformatter 111essentially takes an image from the image detector 102, extracts aportion having a size of about 1920 pixels by 1440 pixels, divides thepixels of this portion into mutually exclusive groups which each have 9pixels arranged in a 3 by 3 format, averages or interpolates the 9pixels of each group into a single calculated pixel, and then maps eachof the calculated pixels to a respective corresponding pixel of thedisplay 117. As still another example, when the zoom factor is at 2×,the reformatter 111 essentially takes an image from the image detector102, extracts a portion having a size of about 1280 pixels by 960pixels, divides the pixels of this center portion into mutuallyexclusive groups which each have 4 pixels arranged in a 2 by 2 format,averages or interpolates the 4 pixels of each group into a singlecalculated pixel, and then maps each of the calculated pixels to arespective corresponding pixel of the display 117.

In the disclosed embodiment, the zoom from 1× to 4× is continuous. Thus,when the zoom factor is between 1× and 2×, between 2× and 3×, or between3× and 4×, the reformatter 111 takes a corresponding portion of an imagefrom the detector 102, and then groups, interpolates and maps the pixelsof this portion into the pixels of the display 117 in a manner analogousto that discussed above. Although the zoom in the disclosed embodimentis continuous, it would alternatively be possible for the zoom factor tobe moved between discrete zoom levels, such as the four discrete zoomlevels of 1×, 2×, 3× and 4×.

During the normal operational mode, if the user presses the MENU button81 (FIG. 3), the sight 10 will enter a menu mode. In this mode,information of the type shown in FIG. 5 is removed from the display 117and is replaced with a menu, an example which is shown in FIG. 6. InFIG. 6, the left side of the display 117 presents list of menuselections, and one of these menu selections is highlighted. The rightside of the display shows various permissible options for most of themenu selections. On the right side of the display, within each group ofoptions, the currently selected option is highlighted.

In the menu mode, the user can scroll through the menu selections on theleft side of the display by pressing either the portion 86 or theportion 87 of the four-way switch 82 (FIG. 3), and the currentlyselected menu selection is highlighted. If the highlighted selection hasoptions shown to its right, the user can scroll through those options bypressing either the portion 88 or the portion 89 of the four-way switch82, and the highlighting will move through these options as thisscrolling occurs.

Each of the menu selections shown on the left side of FIG. 6 will now bediscussed in more detail. The first menu selection is “RECORD MODE”,which permits the user to select whether a specified event will causethe sight 10 to store either a single image, or a video clip. Theseoptions are “IMAGE” or “VIDEO” in FIG. 6, and the selected option willbe reflected in the capture mode indicator 215 of FIG. 5 as “IMG” or“VID”.

The second menu selection in FIG. 6 is the “RECORD RESOLUTION”. Asdiscussed above, a user can select whether each stored image or videoclip is saved with a high resolution or a low resolution, which are therespective options of “HI” and “LOW” in FIG. 6. The selected option willbe reflected in the resolution indicator 216 of FIG. 5 as “HI RES” or“LO RES”.

The third menu selection in FIG. 6 is “COMPRESSION”. This allows theuser to select the amount of compression that will be applied to eachimage or video clip that is stored in the memory card 46, which in turnaffects the amount of memory space required to store that image or videoclip. The sight 10 uses compression techniques of a type known in theart, such as those promulgated by the Joint Photographic Experts Group(JPEG). As shown in FIG. 6, the user can select between options of high,medium and low compression, which are respectively indicated by “HI”,“MED”, and “LOW”.

The next menu selection in FIG. 6 is the “RECORD RETICLE” selection.This option permits the user to select whether or not the currentlyselected reticle will be included or omitted from each saved image orvideo clip. The options are “YES” and “NO”. If the user selects “YES”,then the reticle will be included with the saved information. If theuser selects “NO”, then the reticle will be omitted from the savedinformation.

The next menu selection is “FIRING PIN DETECTION”. This option allows auser to enable and disable the capability of the sight 10 to use theaccelerometer 66 (FIGS. 2 and 4) to detect when a firing pin strikes acartridge in the associated rifle. In particular, the user selects the“ON” option to enable this feature, and selects the “OFF” option todisable this feature. If this feature is enabled, then the firing pindetection indicator 217 in FIG. 5 will read “FP”, whereas if this optionis disabled the indicator 217 will be blank.

When this feature is enabled, each time the sight 10 detects the shockwave caused by the firing pin striking a cartridge, the sight 10 savesin the memory card 46 either a single image or a video clip, dependingon whether the “RECORD MODE” menu selection has been set to “IMAGE” or“VIDEO”, respectively. It will be recognized that, since a video clip isa series of several images, saving a video clip in the memory card 46will take up several times the storage space that would be needed tosave a single image. After saving an image or video clip, the processingsection 106 adjusts the count indicator 214 presented on the display 117(FIG. 5).

In particular, if a single image is stored while in the “IMAGE” mode,then the count indicator 214 will be decremented in order to reflect thenumber of additional images that can be stored in the remaining storagespace at the currently selected resolution and compression. On the otherhand, if a video clip is saved while in “VIDEO” mode, then the value ofthe indicator 214 will be reduced by an amount which corresponds to thenumber of images in the video clip, so that the indicator 214 willreflect the number of additional video clips that can be stored in theremaining storage space at the currently selected resolution andcompression.

If the “FIRING PIN DETECTION” menu selection is set to “OFF”, the sight10 will not detect the event of the firing pin striking a cartridge, andthus will not automatically save an image or a video clip. Instead,however, each time the user manually presses the SHUTTER switch 83 onthe switch panel 76 (FIG. 3), the sight 10 will save either a singleimage or a video clip, depending on which option is currently selectedby the user in the “RECORD MODE” menu selection.

The next menu selection in FIG. 6 is the “AUTO STANDBY” menu selection.The user can set this feature to be either “ON” or “OFF”. When thisfeature is turned on, and when the sight 10 is turned on, the sight 10continuously looks for certain types of activity, including manualactivation of any switch, or any output from certain sensors that isabove a selected threshold, one example of which is detection by theaccelerometer 66 of the firing pin striking a cartridge. If there is nodetected activity during any time internal of 2.5 minutes, the sight 10will cause the displayed reticle 201-205 to begin flashing. Then, ifthere is no detected activity during the next 30 seconds, the sight 10will automatically transition to a power-saving standby state at the endof the 30 second period. In the standby state, the sight 10 monitors theswitches and selected sensors and, when it detects any activity by anyswitch or selected sensor, automatically transitions back to the onstate. Alternatively, if any activity is detected during the 30-secondtime interval while the reticle is flashing, the sight 10 willautomatically stop flashing the reticle and will remain in the on state,rather than transitioning to the standby state.

On the other hand, if the “AUTO STANDBY” menu selection is set to the“OFF” option, then while the sight 10 is turned on, it will alwaysremain in its fully operational mode, without regard to whether or notthere is switch or sensor activity, and will not transition into or outof the power-saving standby mode.

The next menu selection in FIG. 6 is the “VIDEO OUT FORMAT” menuselection. This selection allows the user to specify whether videoinformation which the sight 10 outputs through the connector 148 will bein “NTSC” format or “PAL” format.

The next menu selection is “AUTOMATIC BALLISTIC COMPENSATION”, whichdetermines whether or not this feature is enabled. In particular, theuser selects “YES” to enable this feature, or selects “NO” to disablethis feature. The operation of the automatic ballistic compensationfeature will be described in more detail later.

The next menu selection in FIG. 6 is “RETICLE SELECTION”. It will benoted that this menu selection does not have any options displayed toits right in FIG. 6. If the user scrolls to the “RETICLE SELECTION” menuselection, and then presses the MENU button 81 (FIG. 3), the sight 10will replace the menu of FIG. 6 with a reticle selection screen. FIG. 7is a diagrammatic view of the reticle selection screen.

In FIG. 7, the currently-selected reticle is shown in the center of thedisplay 117, and the names of the two to four available reticles areeach presented in a respective corner of the screen, with the name ofthe currently-selected reticle highlighted. The information shown inFIG. 7 is superimposed on the image of the scene 101 which is currentlybeing detected by the image detector 102. The user can use the four-wayswitch 82 to switch the highlighting from the current-selected reticleto any other available reticle, in which case that reticle will bedisplayed. If the user then presses the “MENU” button 81, thecurrently-selected reticle will become the selected reticle, and thesight 10 will return to the menu screen of FIG. 6.

Alternatively, and still referring to FIG. 7, the user can also use thefour-way switch 82 to highlight the option “Zero Elevation and Windage”in the top center of the display. The user can then press the MENUbutton 81, which will cause the display to switch from the screen ofFIG. 7 to the screen which is shown diagrammatically in FIG. 8, andwhich is used to set elevation and windage offsets for thecurrently-selected reticle.

In particular, pressing the portion 88 or the portion 89 of the four-wayswitch 82 will move the position of the reticle leftwardly orrightwardly in relation to the image presented on the display 117, inorder to adjust for windage, the amount of movement being indicated inthe lower left corner of the screen. Similarly, pressing the portion 86or the portion 87 of the four-way switch 82 will cause the reticle tomove upwardly or downwardly with respect to the display 117, to serve asan elevation adjustment. The amount of the elevation adjustment isindicated in the lower right portion of the screen. At the bottom of thescreen, the label “PRESS MENU TO ZERO”, is always highlighted. Pressingthe MENU button 81 (FIG. 3) will result in a not-illustratedconfirmation request of “Zero Here?”. Selecting “NO” and pressing theMENU button 81 will discard the windage and elevation adjustments madein the screen of FIG. 8, and leave the windage and elevation adjustmentat their prior values. On the other hand, selecting “YES” will save theadjustments made in the screen of FIG. 8 as the new windage andelevation “zero” values, and then the sight 10 will return directly tothe operational display shown in FIG. 5 (except that the windage andelevation offsets displayed at 211 and 212 will each be zero). In FIG.5, the reticle is displayed in the center of the screen, and the imageof the scene 101 is offset relative to the reticle by the amounts of theselected windage and elevation offsets.

Referring again to the menu shown in FIG. 6, the next menu section isthe “REVIEW” selection. The user can use this selection to review theimages or video clips which have been stored in the memory card 46 ofthe sight 10. In particular, if the user selects the “REVIEW” selectionand then presses the “MENU” button 81, the menu of FIG. 6 will bereplaced with an image display screen, which is shown diagrammaticallyin FIG. 9.

Referring to FIG. 9, if there are no saved files with images or videoclips, then the not-illustrated phrase “No Images Saved” will appear onthe display. Otherwise, the image of the last saved file will bepresented in the center of the display 117, as indicateddiagrammatically at 251. If the last saved file contains a video cliprather than a single image, then the first image or frame of the videoclip will be displayed. The name of the last file is shown in the topcenter of the display. If there is more than one saved file, then thetriangular icons 253 and 254 will be presented on opposite sides of thefile name, in order to indicate that the portions 88 and 89 of thefour-way switch 82 can be used scroll successively through the files ineither a forward or reverse direction.

A label “PRESS MENU FOR OPTIONS” appears at the bottom of the screen ofFIG. 9. If the user presses the menu button 81, an options menu isoverlaid on the image 251, as shown diagrammatically in FIG. 10. Theuser can then use the portions 86 and 87 of the four-way switch 82 toscroll through and highlight one of these menu options, and can pressthe MENU button 81 in order to select the highlighted option. The firstoption is “SCOPE DISPLAY”, which immediately returns the sight 10 to itsnormal operational mode, where the display 117 presents the screen ofFIG. 5. In FIG. 10, the second option is “PLAY VIDEO”, which will appearonly if the file under review is a video clip, and which will cause thevideo clip to be played for the user. When the video clip completes, thesight 10 will return to the screen of FIG. 9, and will again display thefirst image of the current video clip.

The third option in the menu of FIG. 10 is “DELETE CURRENT IMAGE”. Thispermits the user to delete the file containing the current image orvideo clip. If the user selects this option, the sight 10 will presenton the display 117 a not-illustrated prompt, asking the user to confirmthat the current file is to be deleted. The sight 10 will then deletethe file if the user confirms that it is to be deleted.

The final selection in the menu of FIG. 10 is “DELETE ALL IMAGES”. Ifthe user selects this option, the sight 10 will present on the display117 a not-illustrated prompt, asking the user to confirm that all savedfiles are to be deleted. The sight 10 will then delete all such files ifthe user confirms that they are to be deleted. When the user selectseither of the last two options in the menu of FIG. 10, and regardless ofwhether the user does or does not actually delete one or more files, thesight 10 will return the user to the screen of FIG. 9, showing eitherthe current image if it was not deleted, or the next available imagewhich has not been deleted.

Referring again to FIG. 6, the next available selection in theillustrated menu is the “GPS Mode” selection. If the user highlightsthis selection and then presses the “MENU” button 81, the sight 10 willuse information received through the GPS antenna 28 and the GPScircuitry 156 to determine the current location of the sight 10 on thesurface of the earth. The sight 10 will then present on the display 117an appropriate portion of some map data stored in the memory card 46 ofthe sight 10, and will superimpose an icon on this map to indicate thecurrent location of the sight 10. This is carried out using techniqueswhich are known in the art of GPS devices. The map data used for thisGPS function can be downloaded into the memory card 46 of the sight 10through the connector 146 (FIG. 4). The user can press the MENU button81 to exit the GPS mode and return to the normal operational mode, inwhich the display 117 presents a screen of the type shown in FIG. 5.

Referring again to FIG. 6, the final menu selection is the “GAME CALL”selection. The user can download into the memory card 46 through theconnector 146 one or more files, which each contain informationrepresenting an audio sound, typically a respective animal sound of atype commonly known as a game call. In some cases this may be a soundmade by one type of animal, such as a mating call, which will tend toattract other animals of the same type. In other cases, this may be asound made by one type of animal, such as a cry of distress, which wouldtend to attract a different type of animal that is a predator of thefirst type.

If the user selects the “GAME CALL” selection in the menu of FIG. 6, andthen presses the MENU button 81, the sight 10 will replace the menu ofFIG. 6 with a not-illustrated menu that lists each of the game callfiles that the user has downloaded into the sight 10. The user can thenuse the four-way switch 82 to scroll among and select one of these gamecalls, and then can press the MENU button 81 in order to select thisparticular game call and return to the sight 10 to its normaloperational mode, in which the display 117 presents a screen of the typeshown in FIG. 5. Thereafter, whenever the user presses the GAME CALLbutton 84 (FIG. 3), the circuitry within the sight 10 uses the speaker68 to produce the audio sound of the currently-selected game call.

As mentioned above, one of the selections in the menu of FIG. 6 is the“AUTOMATIC BALLISTIC COMPENSATION” selection. This feature can also bereferred to as automatic aimpoint adjustment. Before explaining thisfeature in detail, some background information is appropriate.

The trajectory of a bullet or other projectile is determined by the lawsof motion. A bullet exits the barrel of a firearm along the bore line,with a muzzle velocity which is determined by factors such ascharacteristics of the rifle and characteristics of the cartridge. Thecharacteristics of a cartridge can include factors such as the amount ofpowder in the cartridge. Once the bullet has left the rifle, externalforces that act on the bullet can cause changes in the trajectory of thebullet's flight. The primary forces that influence the bullet aregravity, wind and drag.

In a vacuum, when a bullet is fired horizontally, the horizontalvelocity component encounters no resistance and remains constant,whereas the constant force of gravity will cause the bullet to dropvertically, with the overall effect that the bullet follows a well-knownparabolic path. Outside a vacuum, however, air produces drag forces thatslow both the horizontal and vertical components of the velocity of thebullet. As the velocity decreases, there is an increase in the time offlight needed to reach a given range. The longer flight time allows afurther degree of drop due to gravity. Wind forces can also influencethe trajectory of the bullet.

Focusing in more detail on drag, the drag forces on a bullet are due todifferences in pressure acting on the surface of the bullet, and airfriction along the surface of the bullet. These forces are dependent ona number of factors, including the bullet shape and velocity, and thedensity of the ambient atmosphere. Changes in temperature, pressure orhumidity will change the density of the atmosphere from standardsea-level conditions, which in turn can affect the drag forces exertedon a bullet. For example, the density of the atmosphere is lower athigher temperatures, causing a decrease in drag. As another example, thedensity of the atmosphere is higher at higher barometric pressures,causing an increase in drag.

The coefficient of drag as function of bullet velocity has beendetermined experimentally for standard bullets with respect to differentform factors at standard sea-level atmospheric conditions. Mathematicalmodels have been developed that predict velocity retardation for thestandard bullet from factors due to drag. Ammunition manufacturers testtheir bullets, and publish ballistic coefficients that relate thevelocity retardation of their bullets to that of standard bullets.Computer programs have been developed that predict the trajectory of abullet based on various factors, such as the initial muzzle velocity,the ballistic coefficient, gravity, and prevailing environmentalconditions such as wind, pressure, temperature and humidity. One exampleof a software program that is capable of performing these types ofcalculations is the program named “Load from a Disk”, which is availablecommercially from W. Square Enterprises of Houston, Tex.

As discussed above, the disclosed rifle sight 10 includes varioussensors which provide information relevant to bullet trajectories. Thewind sensor 31 provides information regarding the direction and speed ofany prevailing wind, the tilt sensor 61 provides information regardingthe degree of tilt of the rifle about two different axes, the sensor 62provides information about ambient barometric pressure, the sensor 63provides information about ambient temperature and humidity, and therangefinder 26 provides information about the actual range to thetarget.

In addition, the memory 108 of the sight 10 stores tables and/or otherballistic data which are relevant to the calculation of trajectories. Inthe disclosed embodiment, and for simplicity in explaining the presentinvention, it is assumed that the user has downloaded tables or otherballistic data which are specific to the particular bullets and riflethat are being used by the user. Alternatively, however, it would bepossible for the sight 10 to include certain standard data, and topermit the user to use a variation of the above-described menuing systemto select coefficient information from among two or more types ofbullets. The program executed by the processor 107 includes equations orother intelligence of a known type, which permit the processor 107 tocalculate bullet trajectories from the information available to it,including not only the data stored in its memory, but also theinformation which it is currently receiving from the various differentsensors of the sight 10.

When any sight is first mounted on any firearm, it must be initiallyaligned to the firearm, so that a ‘bullet’ will precisely strike atarget at a known range when the aiming reticle is positioned on thetarget. This is normally accomplished through a manual process of trialand error. For example, a person may shoot one or more bullets at atarget which is a known distance away, identify the extent to which thebullets strike the target at locations offset from the location at whichthe person was aiming, and then adjust the alignment of the sight inrelation to the firearm in a manner intended to eliminate the offset.This sequence of steps is repeated in an iterative manner, until bulletsare striking the target at substantially the same location where theperson is aiming.

Once a pre-existing sight has been aligned or “zeroed” in this mannerfor the known range, a person who thereafter uses the firearm and sightmust make allowances both mentally and visually for a variety of factorsthat can differ from the conditions which existed during the initialalignment, including a greater or lesser range, and various atmosphericconditions that can affect drag. In contrast, when the “AUTOMATICBALLISTIC COMPENSATION” selection in the menu of FIG. 6 is enabled, thesight 10 will automatically use its sensors and its stored ballisticdata to accurately calculate the trajectory which will be followed by abullet under the current conditions, and will then calculate anappropriate adjustment needed in the aimpoint. The sight 10 will thenautomatically adjust the relative position of the reticle and the sceneas presented on the display 117 so that, when the user centers thereticle on the target, the bullet can be expected to hit the targetwithout any need for the user to manually and visually attempt to offsetthe reticle in relation to the target, in an attempt to compensate forthe various ambient conditions.

Some specific examples will now be discussed in order to facilitate anunderstanding of how the sight 10 can effect automatic ballisticcompensation when this feature is enabled, or in other words automaticaimpoint adjustment. First, it will be assumed that the automaticballistic compensation feature is not enabled. In this regard, FIG. 11is a diagrammatic view, in which reference numeral 301 represents theentire image detected by the image detector 102 (FIG. 4), and referencenumeral 302 represents the portion of this image which is currentlybeing presented on the color display 117. As discussed earlier, thesight 10 has the capability to select a specific portion of the image301 for presentation on the display 117. In FIG. 11, the display 117shows an image that includes a target 306, which is an animal such as aram. The currently-selected reticle 307 is superimposed on the displayedimage.

The display indicates at 308 that the sight 10 has been zeroed for arange of 200 meters, and indicates at 311 and 312 that the sight isusing the zeroed setting for both windage and elevation. Assume,however, that the actual distance to the target 306 is not 200 meters,but 400 meters. Since the automatic ballistic compensation feature isnot enabled, if a person using the rifle simply centers the reticle 307on the target 306, as shown in FIG. 11, the bullet will fall short ofthe target.

Now assume the same situation, but with the automatic ballisticcompensation feature enabled. The sight 10 will use its various sensorsto determine the current temperature, pressure, humidity, wind speed,wind direction, and range to target, and the tilt of the sight and riflein two dimensions. Then, using this information in combination withknown equations and the stored ballistic information for the particulartype of bullet and rifle which are being used, the sight 10 willcalculate a trajectory to the target 306, and display the reticle 307 atthe expected target impact point.

In this regard, FIG. 12 is a diagrammatic view similar to FIG. 11, butshowing that the sight 10 has automatically shifted the displayed image302 relative to the detected image 301, so that the reticle 307identifies the expected impact point of the bullet within the detectedscene. It will be noted that the indicator 308 has been automaticallyadjusted to show that the actual range to the target is 400 meters, andthe indicator 312 shows that the elevation setting has beenautomatically adjusted to compensate for the difference between thecalibrated range and the actual range.

If the person using the rifle and sight now raises the outer end of thebarrel of the rifle, the target 306 will move downwardly within thedetected image 301, until the reticle 307 is centered on the target 306.In this regard, FIG. 13 is a diagrammatic view similar to FIG. 12, butshowing how the reticle 307 has been centered on the target. Theexpected impact point of the bullet is now centered on the target 306,and the bullet should accurately hit the target. It will be noted thatthe person using the rifle and sight does not need to try to make anymental estimate of a reticle offset intended to compensate for variousfactors such as ambient temperature, pressure, humidity, wind and rangeto target, and does not need to visually offset the reticle 307 from theactual target 306 by this estimated amount.

As another example, assume that the person using the rifle and sightfinds it necessary when taking aim to tilt the rifle and sight a fewdegrees about the longitudinal axis of the barrel. FIG. 14 is adiagrammatic view showing the detected image 301 under thesecircumstances, and showing the portion 302 of this image which would bedisplayed when automatic ballistic compensation is disabled. In FIG. 14,321 represents a bore line of the rifle, 322 represents the angle α oftilt or roll of the rifle and sight about a longitudinal axis, 323represents the direction of the force of gravity, and 326 represents theexpected point of actual impact of the bullet within the detected scene.It will be noted that, in this particular example, the expected point ofimpact is not even within the displayed portion 302 of the detectedimage 301. To try to hit the target, a person using the rifle and sightwould have to make a mental estimate of the amount of reticle offsetneeded, and then try to visually offset the reticle by this estimatedamount, which would be very difficult under these circumstances.

Now assume that the person using the sight 10 enables the automaticballistic compensation feature. The tilt sensor 61 (FIG. 4) will providethe sight 10 with information which includes the tilt or roll angle 322.Using standard trigonometric relationships, the sight 10 can calculatethe horizontal and vertical offsets 331 and 332 which are needed inorder to reposition the portion 302 relative to the image 301 so thatthe reticle 307 will be centered over the expected point of bulletimpact 326.

FIG. 15 is a diagrammatic view similar to FIG. 14, but showing how thesight 10 has automatically repositioned the displayed portion 302 of thedetected image 301 by the offsets 331 and 332 (FIG. 14), so that thereticle 307 is now centered over the expected impact point 326. Theperson using the rifle and sight can then adjust the position of therifle so that the target 306 moves within the image 301 until thereticle 307 is centered on the target 306. FIG. 16 is a diagrammaticview similar to FIG. 15, but showing how the user has centered theadjusted reticle 307 on the target 306. The expected impact point of thebullet now coincides with the target, and the bullet can be expected toaccurately hit the target. Thus, with the automatic aimpoint adjustmentcapability provided by the automatic ballistic compensation feature, theperson using the rifle and sight can position the reticle directly onthe target without any need to try to mentally and visually offset thereticle from the target by an estimated amount that is needed tocompensate for a variety of different environmental factors.

When the sight 10 is in its normal operational mode corresponding to thescreen of FIG. 5, quickly pressing the MENU button 81 twice, or in otherwords “double-clicking” this button, will allow the person using thesight to effect some manual adjustments using the four-way switch 82(FIG. 3). The type of manual adjustment which occurs will depend onwhether or not the automatic ballistic compensation feature is currentlyenabled.

If the automatic ballistic compensation feature is not currentlyenabled, then the operation of the four-way switch 82 will effect atemporary adjustment in the offset on the display 117 between theselected reticle 201-205 and the displayed image. In particular,pressing the portions 86 or 87 of the four-way switch 82 will effectrelative vertical movement of the reticle 201-205 and the displayedimage, and the value of the elevation indicator 212 will be adjusted toreflect the amount of the manual adjustment. Similarly, pressing theportions 88 or 89 of the four-way switch 82 will effect relativehorizontal movement of the reticle 201-205 and the displayed image, andthe value of the windage indicator 211 will be adjusted to reflect theamount of this manual adjustment. When the user presses the MENU button81 again, the sight 10 will discard these temporary adjustments andreturn to its normal operational mode, using the elevation and windagesettings that were in effect before the MENU button was double-clicked.In particular, the windage and elevation adjustments 211 and 212 willeach display a value of zero, and the range indicator 308 will displaythe range for which the firearm and sight are zeroed.

On the other hand, if the automatic ballistic compensation feature isenabled when the MENU button 81 is double-clicked, then operation of thefour-way switch 82 will effect a temporary adjustment in the rangesetting used for the automatic ballistic compensation. In particular,pressing the portions 86 or 87 of the four-way switch 82 will manuallyincrease or decrease the range setting, and the manual value will beused in place of the range information from the rangefinder 26 forpurposes of carrying out automatic ballistic compensation. As the rangeis manually adjusted, the range indicator 218 (FIG. 5) will be adjustedto show the current value of the manually specified range. When the userpresses the MENU button 81 again, the sight 10 will discard thismanually entered range value, and will return to its normal operationalmode, using the range information provided by the rangefinder 26.

Referring again to FIG. 11, a further feature of the sight 10 is that itautomatically adjusts one or more characteristics of the reticle 307 inorder to improve the visibility of the reticle. In the disclosedembodiment, if the reticle 307 is centered on the target 306, and if thetarget 306 is a relatively dark color, the sight 10 will automaticallyselect and use a complementary light color for the reticle 307, suchthat the reticle 307 is highly visible. Conversely, if the reticle 307is centered on a target 306 which is a relatively light color, the sight10 will automatically select and use for the reticle 307 a complementarydark color, so that the reticle 307 is highly visible. In a similarmanner, it would alternatively be possible for the sight 10 to adjustone or more of a variety of other characteristics of the reticle 307,including but not limited to the size, brightness and/or shape of thereticle.

Still another feature is that the sight 10 uses techniques that canimprove the visibility of a target. In this regard, and with referenceto FIG. 11, when the reticle 307 is centered on an object such as atarget 306, the sight 10 uses known image processing and imageenhancement techniques to differentiate the portion of the detectedimage which is the target 306 from other portions of the detected imagewhich are immediately adjacent the target 306, in particular byadjusting one or more characteristics in the displayed image such ascolor, brightness and/or contrast, in order to make the target 306 morehighly visible in relation to its background.

In addition, the sight 10 has the capability to compare each successivepair of detected images of the scene, in order to identify changingpixels that can represent motion. Thus, for example, if an object oranimal which is a prospective target 306 is moving within the detectedscene, the sight 10 can use known image analysis techniques to detectthis motion, and can then adjust one or more characteristics such ascolor, brightness and/or contrast, in order to highlight the detectedmotion in relation to other portions of the detected scene that do notinvolve motion.

The present invention provides a number of advantages. One suchadvantage results from the capability to take information representingone or more current conditions, to use this information to automaticallydetermine an expected point of impact for a projectile, and to thenautomatically adjust a reticle or aimpoint so that it coincides with theexpected point of bullet impact. A related advantage is realized wheresome or all of the information about current conditions is obtainedautomatically using one or more sensors.

A further advantage is realized where a firearm sight has the capabilityto automatically adjust at least one characteristic of a reticle inrelation to a scene on which it is superimposed, for example byadjusting one or more of the color, shape, size, and/or brightness ofthe reticle as a function of the portion of the image on which thereticle is currently superimposed.

Still another advantage results from the provision of capability to useimage processing and enhancement techniques to improve the visibility ofone portion of a scene in relation to the portions surrounding it. Forexample, the portion of a scene on which a reticle is centered can beenhanced in relation to other adjacent portions. Alternatively,successive detected images can be compared in order to detect pixelchanges which represent motion, and the portion of the scene whichcorresponds to detected motion can then be highlighted.

Still another advantage results from the provision of the capability ina rifle sight to receive global positioning system (GPS) signals, and todisplay a portion of a map with an indication on the map of the currentlocation of the firearm sight. A related advantage is realized by thecapability to download selected map information into the rifle sight.

Another advantage is realized where a rifle sight has the capability toselectively generate an audio sound, such as that commonly known as agame call. A further advantage is realized where a set of one or moregame calls can be selected in a computer and then downloaded into therifle sight.

Although one embodiment has been illustrated and described in detail, itwill be understood that various substitutions and alterations arepossible without departing the spirit and scope of the presentinvention, as defined by the following claims.

1. An apparatus comprising a firearm sight which includes: a viewingsection that permits a user to view an image of a scene in associationwith a digital reticle; structure that facilitates the input to saidfirearm sight of information representing a factor that can influence aprojectile trajectory; and a circuit responsive to said information andcooperable with said viewing section for automatically adjusting aposition of said digital reticle in relation to said image as presentedby said viewing section so as to compensate for the extent to which saidfactor would influence a projectile trajectory.
 2. An apparatusaccording to claim 1, wherein said structure includes a sensor forautomatically detecting said factor.
 3. An apparatus according to claim1, wherein said factor is one of a range to a target, a degree of tiltof said firearm sight, a degree of roll of said firearm sight, anambient temperature, an ambient humidity, an ambient pressure, anambient wind speed, and an ambient wind direction.
 4. An apparatusaccording to claim 1, wherein said structure facilitates the input tosaid firearm sight of information representing a further factor that caninfluence a projectile trajectory, said factors being different; andwherein said circuit effects said automatic adjusting of said positionof said digital reticle in response to said information representingeach of said factors so as to compensate for the extent to which each ofsaid factors would influence a projectile trajectory.
 5. An apparatusaccording to claim 4, wherein said structure includes sensor structurefor automatically detecting each of said factors.
 6. An apparatusaccording to claim 4, wherein each said factor is a respective one of arange to a target, a degree of tilt of said firearm sight, a degree ofroll of said firearm sight, an ambient temperature, an ambient humidity,an ambient pressure, an ambient wind speed, and an ambient winddirection.
 7. An apparatus according to claim 1, wherein said firearmsight includes a port through which information relevant to a projectiletrajectory can be introduced electronically into said circuit fromexternally of said firearm sight.
 8. An apparatus comprising: a viewingsection which permits a user to view an image of a scene in associationwith a digital reticle; and structure responsive to said image forautomatically adjusting a characteristic of said reticle.
 9. Anapparatus according to claim 8, wherein said characteristic of saidreticle includes at least one of the color, brightness, size or formthereof.
 10. An apparatus according to claim 8, wherein said structureeffects said adjusting of said reticle so as to improve the contrastbetween said reticle and a portion of said image in the region of saidreticle.
 11. An apparatus according to claim 8, wherein said structureis responsive to a portion of said image in the region of said reticlefor effecting said adjusting of the characteristic of said reticle. 12.An apparatus according to claim 8, including a firearm sight, saidviewing section and said structure being respective portions of saidfirearm sight.
 13. An apparatus comprising: a viewing section whichpermits a user to view a digital image of a scene in association with areticle; and structure for automatically adjusting said digital image todistinguish a first portion of said image which is substantially alignedwith said reticle from a second portion of said image which is adjacentsaid first portion thereof.
 14. An apparatus according to claim 13,wherein said structure effects said adjusting of said digital image byadjusting the contrast between said first and second portions of saidimage.
 15. An apparatus according to claim 13, including a firearmsight, said viewing section and said structure being respective portionsof said firearm sight.
 16. An apparatus comprising a firearm sighthaving structure that can generate an audible sound.
 17. An apparatusaccording to claim 16, wherein said audible sound is an imitation of asound made by an animal.
 18. An apparatus according to claim 16, whereinsaid structure contains definitions of a plurality of audible soundswhich are each an imitation of a sound made by a respective differentanimal; and wherein said structure generates said audible sound from aselected one of said definitions.
 19. An apparatus comprising a firearmsight which includes: a receiver that receives electromagnetic signals;a circuit responsive to said received electromagnetic signals fordetermining a position of said firearm sight on the surface of theearth; and a display, said circuit presenting information on saiddisplay representing the position of said firearm sight on the surfaceof the earth.
 20. An apparatus according to claim 19, wherein saidreceiver is a global positioning system (GPS) receiver, and saidelectromagnetic signals received by said receiver are GPS signals. 21.An apparatus according to claim 19, wherein said circuit includes mapinformation; wherein said information presented by said circuit on saiddisplay includes a selected portion of said map information; and.wherein said circuit effects said presentation on said display of saidfirearm sight at an appropriate location on said selected portion ofsaid map information.
 22. A method of operating a firearm sight,comprising: providing on a viewing section an image of a scene inassociation with a digital reticle; receiving information-representing afactor that can influence a projectile trajectory; and automaticallyadjusting a position of said digital reticle in relation to said imageas presented on said viewing section so as to compensate for the extentto which said factor would influence a projectile trajectory.
 23. Anapparatus according to claim 22, including using a sensor toautomatically detect said factor.
 24. An apparatus according to claim22, including selecting for use as said factor one of a range to atarget, a degree of tilt of said firearm sight, a degree of roll of saidfirearm sight, an ambient temperature, an ambient humidity, an ambientpressure, an ambient wind speed, and an ambient wind direction.
 25. Anapparatus according to claim 22, including receiving informationrepresenting a further factor that can influence a projectiletrajectory, said factors being different; and wherein automaticallyadjusting is carried out so as to compensate for the extent to whicheach of said factors would influence a projectile trajectory.
 26. Anapparatus according to claim 25, including using a sensor arrangement toautomatically detect each of said factors.
 27. An apparatus according toclaim 25, including selecting for use as each said factor a respectiveone of a range to a target, a degree of tilt of said firearm sight, adegree of roll of said firearm sight, an ambient temperature, an ambienthumidity, an ambient pressure, an ambient wind speed, and an ambientwind direction.
 28. An apparatus according to claim 22, includingreceiving electronically through a port from externally of said firearmsight information which is relevant to a projectile trajectory.
 29. Amethod comprising: presenting for a user on a viewing section an imageof a scene in association with a digital reticle; and automaticallyadjusting a characteristic of said reticle in response to said image.30. A method according to claim 29, including selecting as saidcharacteristic of said reticle at least one of the color, brightness,size or form thereof.
 31. A method according to claim 29, wherein saidautomatic adjusting includes improving the contrast between said reticleand a portion of said image in the region of said reticle.
 32. A methodaccording to claim 29, wherein said automatically adjusting is carriedout as a function of a portion of said image in the region of saidreticle.
 33. A method comprising: presenting for a user on a viewingsection a digital image of a scene in association with a reticle; andautomatically adjusting said digital image to distinguish a firstportion of said image which is substantially aligned with said reticlefrom a second portion of said image which is adjacent said first portionthereof.
 34. A method according to claim 33, wherein said automaticallyadjusting includes adjusting the contrast between said first and secondportions of said image.
 35. A method comprising generating of an audiblesound from a firearm sight.
 36. A method according to claim 35,including selecting as said audible sound an imitation of a sound madeby an animal.
 37. A method according to claim 35, including: providingdefinitions of a plurality of audible sounds which are each an imitationof a sound made by a respective different animal; selecting one of saiddefinitions; and carrying out said generating of said audible soundusing said selected definition.
 38. A method of operating a firearmsight having a display, comprising: receiving electromagnetic signals;determining in response to said received electromagnetic signals aposition of said firearm sight on the surface of the earth; andpresenting information on said display which represents the position ofsaid firearm sight on the surface of the earth.
 39. A method accordingto claim 38, wherein said receiving is carried out using globalpositioning system (GPS) signal as said electromagnetic signals.
 40. Amethod according to claim 38, including providing map information withinsaid firearm sight; and wherein said presenting includes presenting onsaid display a selected portion of said map information with anindication on said selected map information of said position of saidfirearm sight on the surface of the earth.